SEATTLE (AP) The contracting team hired to dig a highway tunnel under downtown Seattle told the Washington state Transportation Department on Feb. 10 that it will take months to fix broken seals on the world's largest tunneling machine, the Transportation Department said.
Seattle Tunnel Partners is working with Hitachi Zosen, the machine's manufacturer, to determine how best to fix the broken seals surrounding the main bearing of the machine called “Bertha,'' which is 60 ft. (18 m) underground, Transportation officials said in a statement.
The contractor is looking at accessing the area through the back of the machine or by drilling a shaft in front of it.
“Either way, this process will take months,'' the Transportation Department said.
The machine has been mostly idle for two months and is only one-tenth of the way toward completing a 1.7-mi. (2.7 km) tunnel. The tunnel will carry Highway 99 traffic and allow the removal of the aging Alaskan Way Viaduct along the Seattle waterfront.
Chris Dixon, director of Seattle Tunnel Partners, told The Seattle Times that his team is considering “four or five options'' for a front-end approach.
Once the shaft was dug, the 630-ton (571.5 t) cutter head would be detached and lifted using a crane, the newspaper said.
Dixon said a decision hasn't been made yet. Depending on what inspections show, the contractor might be able to deliver the parts through the back of the machine.